An electric connector used for hot-line connection of electric power lines and the like for transmitting high voltage, high-current electric power may cause an arc discharge between a pair of contacts when the other connector to which the electric connector is connected is pulled, due to high electric energy that has been accumulated between the contacts contacting each other. Such arc discharge may also be caused by induced electromotive force produced when one connector connected to an inductive load is pulled out of the other connector connected to an electric power line.
Arc discharge is a cause of acceleration in degradation, such as erosion of the contacts of an electric connector. The problem has been addressed by largely two methods. The first method, as disclosed in JP-A-2010-56055 (Patent Literature 1), is aimed at preventing the damage to the contacts due to arc discharge by installing a permanent magnet and the like in a direction perpendicular to the opposed direction of a pair of contacts so as to apply a magnetic field and deflect the direction of arc by Lorentz force.
The second method is designed to prevent the development of arc discharge by decreasing the very electric energy accumulated between a pair of contacts. The electric energy stored between a pair of contacts is proportional to the voltage and current between the pair of contacts. Thus, in JP-A-63-86281 (Patent Literature 2) or JP-UM-4-2467 (Patent Literature 3), the voltage between a pair of contacts at the time of separation of the contacts is decreased to prevent the development of arc discharge.
Specifically, in a contact contacting structure 100 described in Patent Literature 2 as illustrated in FIG. 6, a contact 101 and a resistor 102 having a higher electric resistivity ρ than the contact 101 are disposed continuously along a movement path along which a contact 103 of the counterpart connector moves. When the other contact 103 is pulled along the movement path for separation, the contact 103 is separated at a distal end 102a of the resistor 102 where the resistance value is highest, so that the voltage therebetween does not reach an arc-discharge causing voltage, thereby preventing the development of arc discharge.
In a contact contacting structure 110 described in Patent Literature 3, as illustrated in FIGS. 7A and 7B, a contact 112 is provided with increasing resistance value in a separating direction (to the right in the figure) along the movement path of a counterpart contact 114. Thus, when the counterpart contact 114 is pulled along the movement path from its completely inserted state illustrated in FIG. 7A to the state of FIG. 7B, a distal end 112a portion of the contact 112 to which the contact 114 is proximate has the highest resistance, whereby a large potential drop is caused in the contact 112, preventing the development of an arc-discharge causing voltage between the distal end 112a and the contact 114.